1. Field of the Invention
The present invention relates to a photoreceptor for electrophotography used in an electrophotographic process, bishydrazone compounds and intermediates thereof which are suitably used therefor, and a method for producing the bishydrazone compound and the intermediate thereof.
2. Description of the Related Art
There are various methods for the electrophotographic process. Typical examples thereof which have been conventionally known include a direct method and a latent image transfer method. In a photoreceptor for electrophotography used in such an electrophotographic process, a material of a photosensitive layer with a photoconduction function is required to have the following basic properties:
(1) high chargeability by a corona discharge in a dark place; PA1 (2) little loss of an electric charge obtained by a corona discharge in a dark place; PA1 (3) quick diffusion of an electric charge by photoirradiation; PA1 (4) little residue charge after photoirradiation; PA1 (5) minimal increase in the residue charge and minimal decrease in the initial charge in a repeated use; and PA1 (6) minimal variation in the electrophotographic characteristics due to temperature and humidity. PA1 (a) poor compatibility with a binding agent; PA1 (b) being easily precipitated as crystals; PA1 (c) variation in photosensitivity as a result of repeated use; PA1 (d) poor chargeability and poor repeatability; and PA1 (e) poor residue potential characteristic. PA1 "a" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 and m represents an integer of 1 to 5, wherein, if m is 2 or greater, a plurality of "b" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "a" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "a" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring, PA1 wherein the intermediate is a compound represented by the following general formula (IVa): ##STR7## PA1 "a" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 wherein the intermediate is a compound represented by the following general formula (Va): ##STR9## PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "a" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 n represents an integer of 1 to 3, wherein, if n is 2 or greater, a plurality of "a" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 l and w each represent an integer of 1 to 5, wherein, if l is 2 or greater, a plurality of "h" substituents may be identical to or different from one another, or the substituents may form a ring and, if w is 2 or greater, a plurality of "d" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 q represents an integer of 1 to 14, wherein, if q is 2 or greater, a plurality of "e" substituents may be identical to or different from one another, or the substituents may form a ring; and PA1 p represents an integer of 2 to 5. PA1 r represents an integer of 1 to 8, wherein, if r is 2 or greater, a plurality of "e" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 t represents an integer of 1 to 14, wherein, if t is 2 or greater, a plurality of "f" substituents may be identical to or different from one another, or the substituents may form a ring; and PA1 s represents an integer of 2 to 5. PA1 u represents an integer of 1 to 8, wherein, if u is 2 or greater, a plurality of "f" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 q represents an integer of 1 to 14, wherein, if q is 2 or greater, a plurality of "e" substituents may be identical to or different from one another, or the substituents may form a ring; PA1 p represents an integer of 2 to 5; PA1 "f" represents a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; PA1 t represents an integer of 1 to 14, wherein, if t is 2 or greater, a plurality of "f" substituents may be identical to or different from one another, or the substituents may form a ring; and PA1 s represents an integer of 2 to 5. PA1 r represents an integer of 1 to 8, wherein, if r is 2 or greater, a plurality of "e" substituents may be identical to or different from one another, or the substituents may form a ring; PA1 "f" represents a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 u represents an integer of 1 to 8, wherein, if u is 2 or greater, a plurality of "f" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 R.sup.3 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, or a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms; PA1 "g" represents a substituted or unsubstituted alkyl group which has 1 to 3 carbon atoms, a substituted or unsubstituted fluoroalkyl group which has 1 to 5 carbon atoms, a substituted or unsubstituted perfluoroalkyl group which has 1 to 5 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 v represents an integer of 1 to 3, wherein, if v is 2 or greater, a plurality of "g" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "i" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 k represents an integer of 1 to 3, wherein, if k is 2 or greater, a plurality of "i" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 y represents an integer of 1 to 8, wherein, if y is 2 or greater, a plurality of "j" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 y' represents an integer of 1 to 10, wherein, if y' is 2 or greater, a plurality of "j" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "i" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 k represents an integer of 1 to 3, wherein, if k is 2 or greater, a plurality of "i" substituents may be identical to or different from one another, or the substituents may form a ring. PA1 "i" represents an alkyl group which has 1 to 3 carbon atoms, an alkoxy group which has 1 to 3 carbon atoms, a dialkylamino group which has 1 to 3 carbon atoms, a halogen atom, or a hydrogen atom; and PA1 k represents an integer of 1 to 3, wherein, if k is 2 or greater, a plurality of "i" substituents may be identical to or different from one another, or the substituents may form a ring.
As a material having such properties, inorganic photoconductive materials have been conventionally used, such as zinc oxide (Japanese Patent Publication for Opposition No. 57-19780), cadmium sulfide (Japanese Patent Publication for Opposition No. 58-46018), and an amorphous selenium alloy. However, the following problems have been recently pointed out associated with the inorganic materials: in the case of the zinc oxide type material, due to a sensitizing agent, the chargeability by the corona discharge deteriorates and light fading occurs by exposure to light, and therefore a stable image cannot be obtained for a long term; in the case of the cadmium sulfide type material, a stable image cannot be obtained under humid conditions; and the selenium type material has problems such as thermal instability, characteristics deterioration due to crystallization, and difficulty in production.
Thus, from a long-term perspective, researches have been actively conducted for a photoreceptor made of an organic material rather than the inorganic material which has production-related problems due to possible exhaustion of the source materials, and raises a pollution concern due to the toxicity and other environmental problems. As a result, photoreceptors for electrophotography using various organic compounds have been researched. Especially, recently, the function-separated photosensitive layers have been positively researched and developed. Among others, a dominant method has been to negatively charge a charge transfer surface by successively forming, on a conductive support, a charge generation layer and a charge transfer layer which has a positive hole transferring property.
Such function separation has enabled independent development of a material having the charge generation function and a material having the charge transfer function. As a result, various charge generation substances and charge transfer substances have been developed with various molecular structures. Typical examples of such a charge transfer substance which have been developed may be classified as follows by their structural characteristics: a hydrazone type compound (Japanese Laid-open Publication No 54-59143); a stilbene/styryl type compound (Japanese Laid-open Publication No. 58-198043); a triarylamine type compound (Japanese Patent Publication for Opposition No. 58-32372); a phenothiazine type compound; a triazole type compound; a quinoxaline type compound; an oxadiazole type compound; an oxazole type compound; a pyrazoline type compound; a triphenylmethane type compound; a dihydronicotinamide compound; an indoline compound; a semicarbazone compound; etc.
A photoreceptor for electrophotography using such organic compounds is produced by applying a photosensitive layer on a conductive support. A baker applicator, a bar coater, and the like, are known as means for producing a sheet-form photoreceptor, and a spraying method, a vertical ring method, a dip-coat method, and the like, are known for producing a drum-form photoreceptor. The dip-coat method requires only a simple apparatus and thus has been typically employed.
Although various organic compounds have been developed for use as the charge transfer substance, as described above, no organic compound has been developed which can solve all of the following problems:
Moreover, no organic compound has been developed which satisfies the above (1)-(6) basic properties required for a photoreceptor for electrophotography, or those which satisfy further requirements such as mechanical strength or durability.
The inventors of the present invention have conducted a research for a photoconductive material having high sensitivity and high durability, and found that it is effective to use a bishydrazone compound represented by the following general formula (Ia), (Ib) or (Ic) into a photosensitive layer: